Hyperthermia involves the heating of living tissues for therapeutic purposes, such as for increasing blood flow to a particular part of the body. Hyperthermia has been used as a method of treating tumors by means of raising the temperature of the tumor locally, or in the region surrounding the tumor. Hyperthermia can also be effective in reducing adipose tissue through fatty cell necrosis or apoptosis.
Electromedical methods and apparatus for removing target tissue have been disclosed in conjunction with various therapeutic procedures, some of which are non-invasive. For example, U.S. Pat. No. 4,527,550 to Ruggera et al. discloses a radio-frequency diathermy apparatus, including means for localizing the heat focus for eliminating tumor cells. U.S. Pat. No. 4,397,313 to Vaguine discloses a microwave hyperthermia apparatus, including a means for focusing electromagnetic energy at a particular region of the body. U.S. Pat. No. 3,958,559 to Glenn et al. discloses an ultrasonic transducer for focusing ultrasonic waves for non-invasive treatment of internal structures, for example, tumors, within the body.
Although these systems are useful for non-invasive treatment of target tissues, none are specifically directed to the more general application of removing either tumor cells in deeper tissue layers or fat cells within a largely intact subcutaneous fat layer. In fact, each of these systems recognizes the inherent differences between fatty tissue and tumor tissue and teaches the need for avoiding damage to adipose and other normal tissues adjacent to the tumor. Vaguine and Glenn, for example, point to the differing heat tolerance of tumor cells in the context of preserving fatty and other cells adjacent the target tumor cells, not reducing them. Furthermore, the device disclosed by Vaguine uses an element field polarization more appropriate for treating deep tissues below the fat layer, rather than for treating the fat layer itself.
Accordingly, those skilled in the art would desire a generally applicable substantially non-invasive microwave applicator that could be used to induce hyperthermia in living tissue for therapeutic purposes such as either tumor removal or fatty cell necrosis.